Effects of soil tillage on soil compaction, available soil water, and development of common bean

The effects of three tillage methods (moldboard ploughing, disking, and no- tillage) on soil compaction, available soil water, root development, and co mmon bean (Phaseolus vulgaris L.) yield were evaluated. The experiment was carried out on a Dark Red Latosol, under center pivot sprinkler irrigation, which allows cropping twice a year. The soil under moldboard ploughing sho wed the lowest resistance to penetration throughout the profile, whereas un der disking the soil showed a compacted layer between 10 and 24 cm deep. Hi gher compaction until 15-22 cm was observed under no-tillage. Crop roots we re more uniformly distributed throughout the soil profile under moldboard p loughing, whereas under disking and no-tillage roots concentrated in the to p 10 and 20 cm of soil, respectively. The lowest resistance to penetration and the more uniform root distribution throughout the soil profile under mo ldboard ploughing did not reflect on higher yield of common bean as compare d to the other tillage methods, when under irrigation. The highest yield ob served under no-tillage was due, in part, to the lower values of soil water matrix tension observed, and to the smaller variation in this parameter al l over the crop cycle, as opposed to the other methods of soil tillage.